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which ports need to be public for vpn l2tp access through the firewall

1635 Views 5 Replies Latest reply: Oct 29, 2013 9:14 AM by pmlst097 RSS
pmlst097 Level 1 Level 1 (0 points)
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Oct 26, 2013 12:07 PM

I have setup VPN L2TP on my macbook pro,  I can access the VPN on my iPad locally just fine.  When I try to access it through the internet, externally, I receive the message ( on my iPad) "The L2TP-VPN server did not respond.  Try reconnecting.  If the problem continues, verify your settings and contact your administrator".  I suspect this is due to my router ( apple time capsule ) and its built in firewall. I should be able to put in a rule to allow the ports through.  which ports are necessary?

MacBook Air (13-inch Mid 2013), OS X Mavericks (10.9)
  • MrHoffman Level 6 Level 6 (11,745 points)

    On Time Capsule and AirPort Extreme, shut off the Back To My Mac and enable VPN Passthrough.  That'll have the proper ports enabled for you. 


    As for your question:


    Depending on the exact set-up of the network, L2TP requires UDP ports 500, 1701 and 4500 and the IP-ESP protocol, which is IP protocol 50; ESP.


    Other than ESP (which is protocol 50 and not port 50), these are UDP ports, and not TCP.

    It is common for L2TP passthrough to fail when more than one connection is active.


    As compared with L2TP, PPTP is usually easier to get going when there's NAT around, though PPTP is less secure than L2TP.

    Use of an external firewall-gateway with an embedded VPN server is recommended.  (NAT passthrough is something best avoided.)


    Also ensure your ISP is not blocking VPN connections.  There are ISPs that block server-oriented ports on the residential service tier.  (If you're on a business-class tier, ignore this.)

  • danmcq Level 1 Level 1 (0 points)

    If the VPN server you're trying to connect to is running Mavericks, L2TP is currently broken, without a fix. See here:



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